class Chain{
    constructor(value){
        this.value=value||0
    }
    add(count){
        this.value+=count
        return this
        // 一直返回为对象
    }
    minus(count){
        this.value-=count
        return this
    }
    get(){
        return this.value
    }
}

let ss=new Chain(2).add(99).minus(100)//返回为对象
let bb=ss.get()
console.log(bb);//1
